Mycorrhizal source and neighbour identity differently influence Anthemis cotula L. invasion in the Kashmir Himalaya, India

Whilst the importance of arbuscular mycorrhizal fungi (AMF) in invasive spread of some alien plant species has been recently established, it is unclear how such plants respond to AMF from different geographical sources. Besides, influence of different co-occurring plant species on the AMF-mediated invasiveness of alien species, though rarely investigated, is pivotal to the explicit understanding of the feedback between arbuscular mycorrhizal fungi and alien plant invasions. We therefore examined the influence of local (Kashmir Himalyan isolates) and foreign (isolates from Rajasthan, India) AMF on invasiveness of alien Anthemis cotula vis-a-vis the effect of three common co-occurring neighbours, Conyza canadensis, Galinsoga parviflora and Sisymbrium loeselii. Field studies revealed high incidence of Arum-type mycorrhizal colonization in natural populations of A. cotula and the pot trials confirmed the reliance of its invasiveness on AMF with the more favourable effect of local than foreign AMF. The mycorrhizal colonization intensity in field populations of A. cotula was strongly influenced by neighbour identity with major reduction recorded in the presence of S. loeselii (a cruciferous non-host) in comparison to other con-familial neighbours. Pot experiments confirmed the differential effect of co-occurring species on A. cotula's invasive traits. These results signify that the facilitative role of AMF communities in invasion by some alien plants is contingent upon neighbour identity and the present approach provides not only a framework for further examination of the invasive plant-soil biota feedback, but also many important management implications. (C) 2008 Elsevier B.V. All rights reserved.